Optical module

ABSTRACT

An optical module for use in an optical device is provided. The module includes an optical component and relative reference mount. The optical component is fixed spacially relative to a registration feature. The registration feature is configured to couple to a fixed reference mount.

This application is related to co-pending application Ser. No.09/789,185, filed Feb. 20, 2001 and entitled “OPTICAL MODULE WITH SOLDERBOND”; application Ser. No. 09/789,124, filed Feb. 20, 2001 and entitled“OPTICAL DEVICE”; and application Ser. No. 09/789,317, filed Feb. 20,2001 and entitled “OPTICAL ALIGNMENT SYSTEM”, the contents of which arehereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to optical components used in fabricatingoptical devices. More specifically, the present invention relates to anoptical module which carries an optical, optical-electrical or opticalmechanic component.

Optical devices are being increasingly used in various industries andtechnologies in order to provide high speed data transfer such as infiber optic communication equipment. In many applications there is atransition or an incorporation of optical devices where previously onlyelectrical devices were employed. An optical device typically consistsof a number of components which must be precisely assembled and alignedfor the device to operate and function efficiently. Example componentsinclude fibers, waveguides, lasers, modulators, detectors, gratings,optical amplifiers, lenses, mirrors, prisms, windows, etc.

Historically, optical devices such as those used in fiber optictelecommunications, data storage and retrieval, optical inspection, etc.have had little commonality in packaging and assembly methods. Thislimits the applicability of automation equipment for automating themanufacture of these devices since there is such a disparity in thedevice designs. To affect high volume automated manufacturing of suchdevices, parts of each individual manufacturing line have to becustom-designed.

In contrast, industries such as printed circuit board manufacturing andsemiconductor manufacturing have both evolved to have common designrules and packaging methods. This allows the same piece of automationequipment to be applied to a multitude of designs using printed circuitsas an example, diverse applications ranging from computer motherboardsto cellular telephones may be designed from relatively the same set offundamental building blocks. These building blocks include printedcircuit boards, integrated circuit chips, discrete capacitors, and soforth. Furthermore, the same automation equipment, such as a pick andplace machine, is adaptable to the assembly of each of these designsbecause they use common components and design rules.

Further complications arise in automated assembly of optical devices.Such assembly is complicated because of the precise mechanical alignmentrequirements of optical components. This adds to problems which arisedue to design variations. The problem arises from the fact that manycharacteristics of optical components cannot be economically controlledto exacting tolerances. Examples of these properties include the fibercore concentricity with respect to the cladding, the location of theoptical axis of a lens with respect to its outside mechanicaldimensions, the back focal position of a lens, the spectralcharacteristics of a thin-film interference filter, etc. Even if themechanical mounting of each optical element were such that each elementwas located in its exact theoretical design position, due to thetolerances listed above, the performance specifications of the opticaldevice may not be met.

To appreciate the exacting alignment requirements of high performanceoptical devices, consider the simple example of aligning two single modeoptical fibers. In this example, the following mechanical alignments arerequired to ensure adequate light coupling from one fiber to the other:the angle of the fibers with respect to each other, the fiber faceangle, the transverse alignment (perpendicular to the light propagationdirection) and the longitudinal spacing (parallel to the lightpropagation direction).

Typical single mode optical fibers used in telecommunications for the1.3 μm to 1.6 μm wavelength band have an effective core diameter ofabout 9 microns and an outside cladding dimension of 125 microns. Thetypical tolerance for the concentricity of the core to the outsidediameter of the cladding is 1 micron. If the outside claddings of thetwo fibers were perfectly aligned and there is no angular misalignmentor longitudinal spacing, the cores may still be transversely misalignedby as much as 2 microns. This misalignment would give a theoreticalcoupling loss of about 14 percent or 0.65 dB. This loss is unacceptablein many applications. Techniques using active alignment, such as thatshown in U.S. Pat. No. 5,745,624, entitled “AUTOMATIC ALIGNMENT ANDLOCKING METHOD AND APPARATUS FOR FIBER OPTICAL MODULE MANUFACTURING”,issued Apr. 28, 1998 to Chan et al., can be employed to improve couplingefficiency.

SUMMARY OF THE INVENTION

In one example aspect, an optical module for use in an optical device isprovided. The module includes an optical component and a relativereference mount configured to couple to a fixed reference mount. Bondingmaterial fixedly couples the optical component relative to the relativereference mount. This fixes the position and orientation of the opticalcomponent relative to registration features of the relative referencemount.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an optical device in accordance with oneexample embodiment of the present invention.

FIG. 2A is a exploded perspective view of an optical module shown inFIG. 1.

FIG. 2B is a bottom plan view of a component mount.

FIG. 3 is a front plan view of an optical module of FIG. 1.

FIG. 4 is a bottom plan view of the optical module of FIG. 1.

FIG. 5 is a top plan view of a fixed reference mount shown in FIG. 1.

FIG. 6 is a cross-sectional view of the optical module of FIG. 4 takenalong the line labeled 6—6.

FIG. 7A is a cross-sectional view of registration features used toregister the relative reference mount with a fixed reference mount shownin FIG. 1.

FIG. 7B is an exploded cross-sectional view of the registrationfeatures.

FIG. 8A is a perspective view showing bonding material used with thepresent invention.

FIG. 8B is a side cross-sectional view showing the bonding material ofFIG. 8A.

FIG. 8C is an enlarged view of the bonding material.

FIG. 8D is an enlarged view of the bonding material which illustratesdeformation of the material after heating.

FIG. 9 is a perspective view showing an optical module of the presentinvention which includes a Gradient Index (GRIN) lens.

FIG. 10 is a front plan view of the optical module of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention includes various aspects that reduce or eliminatemany of the problems associated with the prior art. The presentinvention offers an optical component which is prealigned in astandardized optical module. The optical module can be aligned withsub-micron precision with respect to registration features. Registrationfeatures on the module can be aligned with matching features on asubstrate. This is similar to mounting an electrical component in or ona printed circuit board. Optical devices can be easily fabricated bymounting prealigned optical modules in the optical “circuit board”. Theprealignment of the optical component can compensate for variationsbetween components to thereby essentially eliminate the effects ofcomponent variability. The prealigned optical modules are well suitedfor automated fabrication of devices. The modules can be fabricated insilicon using techniques which are well known in the art of siliconprocessing. However, any appropriate material can be used. Preferablematerials are those which are used with existing electrical or opticalcomponents. Further, the invention can be used with active devices suchas lasers, modulators, detectors, etc. Electrical conductors can befabricated on the various layers for coupling to active opticalcomponents. Electrical circuitry including analog and digital circuitry,can also be fabricated directly on the modules or on the fixed referencemount.

In one aspect, the present invention provides an optical module in whichan optical component is mounted to an optical component mount. Theoptical component mount is fixed to a relative reference mount such as abase mounting plate at a desired position and orientation. The relativereference mount is coupled to a fixed reference mount such as asubstrate such that the optical component is maintained at a desiredposition and orientation relative to the fixed reference mount. In thisgeneral configuration, the optical component can be pre-aligned to adesired spacial reference and orientation by adjusting the opticalcomponent mount relative to the reference mount prior to fixing theirrelative positions. This can be used to provide general componentpre-alignment as well as compensate for the variations which can arisebetween optical components. The following description sets forth anumber of specific examples, however, in various aspects, the presentinvention is not limited to the specific configurations, components ortechniques set forth herein.

FIG. 1 is a perspective view of an optical device 10. Optical device 10is shown as a simple optical fiber to optical fiber coupler for purposesof illustrating the present invention. However, the invention isapplicable to more complex or other optical devices and other types ofoptical components.

In FIG. 1, the optical device 10 is fabricated from two optical modules12A and 12B which include respective optical components 14A and 14Billustrated in this specific example as optical fibers. The fibers aremounted to respective optical component mounts 16A and 16B which arepositioned and oriented to achieve a desired position and orientation ofoptical components 14A and 14B relative to base mounting plates 18A and18B, respectively. A number of specific examples of this coupling areset forth below in more detail, however, other aspects of the inventionare not limited to such examples. In the example illustrationsspecifically set forth in FIG. 1, base mounting plates 18A and 18Bcomprise substantially planar mating plates. Base mounting plates 18A,18B are one example of a relative reference mount. The relativereference mount can have any shape or configuration. Base mountingplates 18A and 18B mount to a reference substrate 20 such that theoptical components 14A and 14B are in substantial alignment. Substrate20 is one example of a fixed reference mount and any appropriate fixedreference mount with appropriate shape and configuration can be used.

The optical component modules of the present invention can bepre-assembled and pre-aligned to an appropriate reference such that afinal optical device is fabricated by simply mounting the assembledoptical modules on the reference substrate. In the example of FIG. 1,reference substrate 20 is illustrated as a planar substrate which can bethought of as an optical “circuit board” which receives optical modulesto form an optical, opto-electrical or opto-mechanical device.

FIG. 2A is an exploded perspective view of optical module 12. In thespecific example shown in FIG. 2A, optical component mount or holder 16comprises upper component mount or holder 24 and lower component mountor holder 26. Again, other configurations are within the scope of thepresent invention. FIG. 2A illustrates one example mounting techniquecoupling optical component mount 16 to base mounting plate 18. In thisexample, a bonding material 30 is carried on a top surface of base mountplate 18. Material 30 preferably has at least two states. In one state,material 30 does not interfere or contact mount 16. Then, the opticalcomponent mount 16 can be positioned with up to six degrees of freedomrelative to the base mounting plate 18. In another state, the materialcouples mounts 16 and 18 and thereby fixes the relative positiontherebetween. In one preferred embodiment, material 30 comprises a heator chemically responsive (or activated) material such as solder or otherbonding material. The solder can comprise any type of solder includingplated solder, solder. preforms, solder balls, solder paste, solderbumps, etc. including those types of solders used in flip chipelectronic packages. However, other materials such as adhesives whichdry, chemically react, or are activated by other means or otherattachment techniques can be used. Preferably, the attachment techniqueallows some relative movement between the optical component mount 16 andthe base mounting plate 18 prior to fixedly attaching the two. Inembodiments where a heat activated material is used, heating elements(see FIG. 8B for more detail) can be provided to heat the material 30.For example, in FIG. 2A, heating elements are provided which areactivated through the application of electrical energy through contactpads 34. This can be by electrically contacting pads 34 and applying acurrent therethrough. However, other heating techniques can be used. Ofcourse, other techniques to change the state of bonding material can beused such as application of a curing component such as radiation or achemical. Any appropriate adhesives including brazing, welding, bondingor other technique can be used. The bond can be activated using atechnique including exposure to air, heat, chemicals, heat radiation(including light and UW), etc.

FIG. 2B is a bottom plan view of optical component mount 16 and lowermount 26 and shows bonding pads 40 which are arranged to mate withmaterial 30 shown in FIG. 2A. Pads 40 can comprise, for example, a metaldeposited on lower mount 26.

FIG. 3 is a front plan view of optical module 12 showing opticalcomponent mount 16 adjacent base mounting plate 18. In the arrangementshown in FIG. 3, material 30 is not initially in contact with opticalcomponent mount 16. As discussed below, material 30 can be activated tofill or fix the gap 32 between mount 16 and mount 18. However, othertypes of material 30 can be used in which there is actual contactbetween mounts 16 and 18 or material 30 fills gap 32 prior to bonding.In one preferred embodiment, prior to fixedly adhering mount 16 to mount18 either component can be manipulated through up to six degrees offreedom as illustrated by the axes labeled X and Y in FIG. 3 along withanother Z axis which is not shown and is perpendicular to a plane of theFigure, and rotation about the three axes. For some optical components,all six degrees of freedom may not be required for proper alignment andfewer degrees of freedom can be provided. FIG. 3 also illustratesexample registration features 50. In the example embodiment of FIG. 3,each registration feature 50 is a protrusion which is configured to matewith reference substrate 20 as discussed below.

FIG. 3 also shows a component registration feature 60 formed in lowercomponent mount 26 and a component registration feature 62 in uppercomponent mount 24. In general, any registration technique can be usedand the invention is not limited to the specific example illustratedherein. In the example embodiment, component registration features 60and 62 comprise V-grooves which are configured to receive an opticalcomponent such as optical component 14. The optical element 14 can becoupled to the optical component mount using, for example, an adhesiveor solder. Optical component 14 is preferably fixed to component mount16 to maintain alignment relative to registration features 50 ofrelative reference mount 18.

FIG. 4 is a bottom plan view of optical module 12 which shows basemounting plate 18 and a portion of lower optical component mount 26 ofoptical component mount 16. Pads 54 on base mounting plate 18 can bondwith bonding material 72. The bottom plan view of FIG. 4 illustrates aninterface surface 64 of optical component mount 16. Interface surface 64is an input, output or input/output face for the optical component 14shown in FIG. 3. In some embodiments, the interface surfaces of adjacentoptical modules are in abutting contact. In some embodiments, arefractive index optical matching material fills any gap betweenadjacent interface faces to provide improved coupling and reducereflections. For example, the optical matching material may be in asolid, gel or liquid form. In one example embodiment, interface surface64 is a plane which forms an angle relative to a plane perpendicular tothe direction of propagation of optical fiber 14. For example, this canbe eight degrees. An angled surface 64 of the optical component 14 canbe preferable because it reduces the amount of reflected light which iscoupled back into an optical fiber. If two modules are in closeproximity or in abutting contact, the adjacent optical component mountwould have a complimentary angle. In embodiments where an angle or aspecific interface finish is desired, interface surface 64 can be shapedor formed using an appropriate process such as a lapping process,chemically machining, machining, etc., or an additive process, toachieve the desired configuration. For example, after the opticalcomponent 14 is secured within the optical component mount 16, thesurface 64 can be lapped to achieve the desired angle or surface finish.Such techniques can also be used to ensure that a face of the opticalcomponent is flush with the interface surface 64. However, in someembodiments, it may be desirable to have the optical component 14 eitherrecessed or protruding from interface surface 64.

FIG. 5 is a top plan view of reference substrate 20 configured toreceive optical modules 12A and 12B shown in FIG. 1. Registrationfeatures 70A and 70B are provided to receive registration features 50 onrespective optical modules 12A and 12B. In the example embodiment,features 70 are precisely defined depressions configured to register theprotrusions of registration features 50 shown in FIGS. 3 or 4. Thisexample embodiment is shown in FIG. 7A in more detail. The dashedoutlines indicate the placement of base mounting plates 18A and 18B.This configuration provides an example of a kinematic-type registrationor alignment technique. One example kinematic technique is described inU.S. Pat. No. 5,748,827, entitled “TWO-STAGE KINEMATIC MOUNT”. Anyappropriate registration or alignment technique can be used, however,preferably the registration technique should be accurate and providehigh repeatability. In the example embodiment, a heat activated material72 such as solder is provided which can be heated to fixedly adhere theoptical modules to the reference substrate. In such an embodiment,contact pads 74 electrically couple to heaters which are used to heatmaterial 72. Material 72 is preferably aligned with pads 54 shown inFIG. 4. For example, pads 54 can be of a material to which material 72will strongly adhere. For example, pads 54 can comprise a metal to whichsolder will adhere. Pads used to promote adhesion can have multiplelayers. For example, one layer to bond with the bonding material andanother layer bond with the mount, such as mounts 16, 18 or substrate20.

FIG. 6 is a cross-sectional view showing optical module 12 mounted takenalong the line labeled 6—6 in FIG. 4 and including substrate 20. Thisview shows the assembled configuration in which the optical module 12 iscoupled to the reference substrate 20 and component holder 16 is coupledto base mounting plate 18.

FIG. 7A is an enlarged cross-sectional and FIG. 7B is an enlargedexploded view showing groove registration feature 70 and protrudingregistration feature 50. The relative spacing between plate 18 andsubstrate 20 can be controlled by adjusting the angle or widths of thewalls of v-groove 70 or of protrusion 50. If fabricated in properlyoriented, single crystal silicon, the angle is typically fixed by thecrystal structure of the material and the width can be adjusted tocontrol the spacing. The coupling between plate 18 and substrate 20actually occurs at line contact points 76.

FIG. 8A is a perspective view showing bonding material 30 in greaterdetail and FIG. 8B is a cross-sectional view showing bonding material 30between lower component mount 26 and mounting plate 18. Bonding material30 is carried on heating elements 80 which are electrically coupled toconductors 82. Heating elements 80 can comprise a resistive elementssuch as a refractory metal or alloy such as tantalum, chromium ornichrome and be configured to melt material 30 when sufficientelectrical current is supplied through conductors 82.

The cross-sectional view shown in FIG. 8B illustrates the configurationnear heating element 80. FIG. 8B is a diagram of thin film layers and isnot to scale and shows features, such as contacts 34 which are remotefrom the heater element 80 and near the edge of mounting plate 18.Element 80 is shown electrically coupled to contacts 34 throughelectrical conductors 82. An electrical insulating layer 87 canoptionally be positioned between element 80 and material 30 to increasethe amount of electrical current flowing through element 80. Additionallayer or layers 85 can be deposited on insulator 87 to promote adhesionor provide other characteristics or qualities as desired. This is knownin the art of metal deposition as “under-bump metallurgy.” Thermal(and/or electrical) isolation layers 89 can also be applied to reducethe transfer of thermal energy to the surrounding components.Preferably, heating element 80 is designed to operate in a thermallyadiabatic regime. As current flows through the heating element 80 and itbegins to warm, the thermal energy flows into the bonding material 30.Similarly, the structure preferably is configured to reduce heat flowinto the surrounding areas. This reduces the energy required to activatethe bonding material, reduces the heating and setting times and reducesthe thermal stress applied to the surrounding material. Element 80 canhave any appropriate shape including straight, bifilar, serpentine, etc.Solder provides a bonding material which can be quickly attached (inless than 100 mSec) and allows “reworking” the bond by reheating thesolder.

The various materials can be selected as desired for the appropriatephysical properties. SiO₂ provides good thermal and electrical isolationand is easily processed. Of course, other materials including otheroxides or organic films can be used. The electrical isolation layer 87is preferably relatively thin and provides high thermal conductivity.Silicon nitride is one example material. The conductors 82 can be anyconductive material however, preferable materials include those whichare easily deposited such as thick refractory metals, gold or aluminum.The material or materials for pads 54 can be any appropriate materialwhich adheres to the bonding material 30. Examples include, titanium,gold, nickel, etc. The thickness of the various layers should also beselected to reduce the thermal load on the heating element. Pad 54 isshown with layers 54A and 54B. Layers 54A can be of a material suitablefor bonding to thermal isolation layer 89. For example, Ni if layer 89is SiO₂. Layer 54B is configured to bond with bonding material 30 andmay be, for example, gold, nickel, titanium, or other materials.

As shown in FIG. 8C, in one embodiment, material 30 comprises a solderformed with a large surface area region 84 and a tapered region 86. Whenmaterial 30 is melted, surface tension causes the liquid material fromtapered region 86 to flow toward large surface area region 84 and causelarge surface area region 84 to expand in an upward direction asillustrated in FIG. 8D. This configuration is advantageous because itallows the orientation of component mount 16 to be adjusted as desired(through the six degrees of freedom as discussed with respect to FIG. 3)without any interference from the bonding material 30. Bonding materialonly contacts the two surfaces when heat is applied and the materialfills the gap between the two components. Similarly, with respect tomounting base mounting plate 18 to reference substrate 20, plate 18 canbe securely registered within feature 70 prior to application of thebonding material 72 or actuation of heating elements. Such a solder flowtechnique is described in U.S. Pat. No. 5,892,179, entitled “SOLDERBUMPS AND STRUCTURES FOR INTEGRATED REDISTRIBUTION ROUTING CONDUCTORS”,issued Apr. 6, 1999 which is incorporated herein by reference.

As mentioned above, other bonding techniques including adhesives and UVcuring techniques can be used and the invention is not limited tosolder. However, in one aspect, the bonding technique can advantageouslyuse the surface tension developed in the bonding material. Note that thesolder or adhesive can be electrically conductive to provide electricalcontacts to the optical device between the various layers, or toadjacent electronic circuitry. Thermally conductive materials can beused to help dissipate heat. In another aspect, two bonding materialsare used, which can be the same or different and can be appliedsimultaneously or sequentially. For example, after the solder discussedherein is applied, a second bonding material can fill the gap to provideadditional stability. However, shrinkage or other shape changes of thebonding material should be addressed to maintain alignment. In someembodiments, roughness or texturing the surfaces using any appropriatetechnique can be used to promote adhesion of the bonding material.

Component 14 can be any type of optical opto-electrical oropto-mechanical element including active or passive elements. In theabove examples, optical element 14 is shown as an optical fiber. Toillustrate one alternative example optical module 12, in FIGS. 9 and 10an optical element 90 is shown which comprises a GRIN lens. FIG. 9 is aperspective view showing lens 90 held in component mount 16 whichcoupled to base mounting plate 18. FIG. 10 is a front plan view. Lens 90is registered with a registration groove 60. Additional support bondingmaterial 92 is provided to secure lens 90 to component mount 16. Thiscan be an adhesive, solder or other bonding material.

The various components can be fabricated using any appropriate techniqueor material. In one embodiment, the depressions or grooves for variousregistration features are formed by anisotropically etching orientedsingle-crystal silicon. Protrusions can be formed in an analogous,complimentary manner. The configuration should preferably eliminate orsubstantially reduce movement in any of the six degrees of freedom. Thisis required to achieve sub-micron spacial reproducibility betweencomponents. For example, a [100] orientation of single crystal siliconallows the formation of such features which can be orientated at 90degrees to one another. Any appropriate etching or formation techniquecan be used. One common anisotropic etch technique uses KOH and maskingto define the desired features. Regarding the various conductive layers,heating element layers, and insulating layers, any appropriatesputtering, plating, evaporation or other fabrication technique can beused.

The various aspects of the present invention discussed above provideprealigned optical modules which can reduce or eliminate the effects ofcomponent variability. In the above example, this is achieved byadjusting the component mount (holder) relative to a registrationfeature on the base mounting plate. The bonding material fixes thespacial orientation between the component and registration feature.Precise registration features are provided on the base mounting plate 18such that it can be inserted into an optical “circuit board” tofabricate devices which comprise multiple optical component modules. Theoptical modules are well suited for automated assembly of opticaldevices because they are in standardized packages, prealigned and can beeasily mounted on a reference substrate. Optical modules can be manuallyplaced into the optical “circuit board” or the process can be automated.The particular optical modules are preferably standardized to facilitatesuch automation. Further, this configuration allows assembly of devicesin a “top downward” fashion in which optical modules are moved downwardinto an optical “circuit board” which facilitates process automation.Further, because different modules are fabricated using similarmaterials, variations due to thermal expansion will affect all modulesin a similar way such that the alignment between adjacent modules on theoptical “circuit board” is maintained.

Electrical conductivity of the solder bond can be used advantageously toprovide an electrical connection to electrical components on the module.The solder can be heated in any order or combination includingsimultaneously. The position and sequence of the heating of the soldercan be configured to reduce or compensate for deformation in thecomponents including thermal deformation. Solder can also be usedadvantageously because the solder can be reheated allowing the componentto be repositioned, removed, replaced, and/or repaired.

In one general aspect, the present invention provides an optical modulein which optical variations due to component variability are eliminatedor significantly reduced. This provides uniformity across multipleoptical modules which is particularly desirable for automated assembly.In one aspect, the invention can be viewed as providing three stages ofalignment between the optical component and the optical component mount.A first stage of alignment is provided between the component mount(holder) and the optical component, for example using a V-grooveregistration feature as shown or other technique. A second stage ofalignment is between the optical component mount and registrationfeatures of the relative reference mount. This also eliminates orreduces alignment variations due to component variability. A finalalignment occurs between the optical module and the reference substrate.In another example aspect, the optical element has an opticalcharacteristic which varies in space relative to at least one dimension.The optical component is aligned with reference features on the relativereference mount by fixing the position of the component mount relativeto the registration features of the relative reference mount to therebyalign the optical characteristic. In one aspect, the first stage ofalignment is eliminated and the optical element is directly aligned withthe registration features of the relative reference mount and nomount/holder is used.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, the number of solder, heater,and receiver sets may be altered depending on detailed requirement. Thesequence of reflowing the solder may be altered to enhance stability.The optical component can be any type of active or passive optical,opto-electrical or opto-mechanical component and not limited to thespecific examples set forth herein. The optical component can be alignedand its orientation fixed using any suitable or desirable means. Thespecific components and examples set forth herein are provided todemonstrate various aspects of the invention and do not limit the scopeof the invention. Other elements, shapes, components, configurations,etc. are within the scope of the invention. Any appropriate material canbe used for various components. In one specific aspect, the relativereference mount and other components are formed from a single crystalmaterial such as silicon. In another aspect, these components can befabricated from any electrical material including semiconductors orceramics. Other materials include machinable materials such as steel,aluminum, metal alloys, etc. depending on requirements of a particularimplementation. An assembled optical module can be used to fabricate anoptical device using a “pick and place” machine or any suitable ordesirable means. In such an embodiment, the chamfers or bevels on theedges of the component mount can facilitate mechanical gripping of themount. Similarly, the various components of the invention can befabricated using any desired technique. Solders are known in the art andany appropriate solder can be selected to obtain the desiredcharacteristics. The optical component can be coupled directly to therelative reference mount without a separate component mount. As a usedherein, “light” is not necessarily visible light. Further, the opticalcomponent can be any active or passive optical, opto-electrical oropto-mechanical element. The optical modules can be prealigned using anyappropriate technique for example, the techniques set forth in U.S. Pat.application Ser. No. 09/789,317, filed Feb. 20, 2001 and entitled“OPTICAL ALIGNMENT SYSTEM”. In an example alternative, the alignment isperformed insitu, after the optical module or relative reference mounthas been mounted to the optical “circuit board”.

What is claimed is:
 1. An optical module for use in an optical device,comprising: an optical component having an optical characteristic whichvaries based upon a position of the optical component in space relativeto at least one dimension and wherein component variability causes avariability in the optical characteristic; a relative reference mounthaving a registration feature with a three dimensional shape configuredto constrain movement in six degrees of freedom when physically coupledto a corresponding registration feature of a fixed reference mount andto provide a repeatable is registration therebetween; an adjustableoptical component mount configured to fixedly couple to the opticalcomponent and have an adjustable position relative to the relativereference mount; and a bond configured to bond the optical componentmount to the relative reference mount and thereby fix the opticalcomponent relative to the registration feature of the relative referencemount at a prealigned position relative to the registration feature ofthe relative reference mount to adjust for the variability in theoptical characteristic of the optical component prior to placing therelative reference mount in the fixed reference mount whereby theoptical component is fixed in six degrees of freedom relative to theregistration feature of the relative reference mount.
 2. The opticalmodule of claim 1 wherein the bond comprises solder.
 3. The opticalmodule of claim 1 wherein the bond is electrical conductive.
 4. Theoptical module of claim 1 wherein the optical component mount comprisesfirst and second plates with the optical component secured therebetween.5. The optical module of claim 1 wherein the bond comprises adhesive. 6.The optical module of claim 1 wherein the bond has a first state inwhich the spacial orientation can be adjusted and a second state inwhich the spacial orientation is fixed.
 7. The optical module of claim 6wherein the bond is operably coupled to only one of the opticalcomponent and the relative reference mount when in a first state.
 8. Theoptical module of claim 7 wherein the bond is activated to fill a gap.9. The optical module of claim 6 wherein application or removal of heatcauses a change in state of the bond.
 10. The optical module of claim 6wherein application or removal of radiation causes a change in state ofthe bond.
 11. The optical module of claim 1 wherein the relativereference mount is substantially planar.
 12. The optical module of claim1 wherein the fixed reference mount comprises a substantially planarsubstrate.
 13. The optical module of claim 1 wherein the bond has afirst state in which the optical component can move with up to 6 degreesof freedom relative to the relative reference mount.
 14. The opticalmodule of claim 1 including a bonding pad between the optical componentmount and the relative reference mount configured to adhere to the bond.15. The optical module of claim 1 wherein the optical component mountincludes a registration feature configured to register the opticalcomponent.
 16. The optical module of claim 1 wherein the opticalcomponent is bonded to the optical component mount.
 17. The opticalmodule of claim 1 wherein the bond is heat activated and at least oneheater element is thermally coupled to the bond.
 18. The optical moduleof claim 17 including electrical conductors on at least one of therelative reference mount and the optical component mount electricallycoupled to the heater element.
 19. The optical module of claim 18including contact pads electrically coupled to the electricalconductors.
 20. The optical module of claim 1 including a bonding pad onthe relative reference mount configured to adhere to a bond coupled tothe fixed reference mount.
 21. The optical module of claim 1 wherein therelative reference mount comprises silicon.
 22. The optical module ofclaim 1 wherein the optical component mount comprises silicon.
 23. Theoptical module of claim 1 wherein the optical component mount includesan interface surface and the optical component is flush with theinterface surface.
 24. The optical module of claim 1 wherein therelative reference mount comprises a semiconductor.
 25. The opticalmodule of claim 1 wherein the relative reference mount comprises aceramic.
 26. The optical module of claim 1 wherein the registrationfeature is configured to provide substantially kinematic registration toa fixed reference mount.
 27. The optical module of claim 1 wherein theadjustable position comprises a height adjustment of the opticalcomponent over the relative reference mount.
 28. The optical module ofclaim 1 wherein the bond comprises a weld.
 29. An optical module for usein an optical device, comprising: an optical component having an opticalcharacteristic which varies based upon a position of the opticalcomponent in space relative to at least one dimension and whereincomponent variability causes a variability in the opticalcharacteristic; an adjustable optical component mount having asubstantially planar mount plate coupled to the optical component; asubstantially planar relative reference mount having a registrationfeature with a three dimensional shape configured to constrain movementin six degrees of freedom when physically coupled to a substantiallyplanar fixed reference substrate and to provide a repeatableregistration therebetween; a bond configured to bond the relativereference mount to the optical component mount opposite the opticalcomponent to thereby fix the optical component relative to the relativereference mount at a prealigned position; wherein the adjustable opticalcomponent mount allows adjustment of the optical component relative tothe substantially planar relative reference mount and the bond fixes theadjusted position of the optical component at a prealigned positionrelative to the registration feature of the relative reference mount toadjust for the variability in the optical characteristic of the opticalcomponent prior to placing the relative reference mount in the fixedreference mount whereby the optical component is fixed in six degrees offreedom relative to the substantially planar relative reference mount.30. The optical module of claim 29 wherein the bond comprises solder.31. The optical module of claim 29 wherein the bond comprises adhesive.32. The optical module of claim 29 wherein the bond has a first state inwhich the spacial orientation can be adjusted and a second state inwhich the spacial orientation is fixed.
 33. The optical module of claim32 wherein the bond touches only one of the optical component mount andthe relative reference mount when in a first state.
 34. The opticalmodule of claim 33 wherein application or removal of heat causes achange in state of the bond.
 35. The optical module of claim 29including a bonding pad between the optical component mount and therelative reference mount configured to adhere to the bond.
 36. Theoptical module of claim 29 wherein the bond is heat activated and atleast one heating element is thermally coupled to the bond.
 37. Theoptical module of claim 29 wherein the relative reference mountcomprises silicon.
 38. The optical module of claim 29 wherein theregistration feature is configured to provide substantially kinematicregistration to a fixed reference mount.
 39. The optical module of claim29 wherein the adjusted position comprises height of the opticalcomponent over the relative reference mount.
 40. The optical module ofclaim 29 wherein the bond comprises a weld.
 41. An optical module foruse in an optical device, comprising: an optical component having anoptical characteristic which varies based upon a position of the opticalcomponent in space relative to at least one dimension and whereincomponent variability causes a variability in the opticalcharacteristic; an adjustable optical component mount configured tofixedly couple to the optical component; a relative reference mounthaving a registration feature with a three dimensional shape configuredto constrain movement of the adjustable optical component mount in sixdegrees of freedom when physically coupled to a reference substrate andto provide a repeatable registration therebetween and allow relativeadjustment of the position of the adjustable optical component mount;and an adjusted fixed spacial orientation between the optical componentmount and the relative reference mount to prealign the optical componentrelative to the registration feature of the relative reference mount toadjust for the variability in the optical characteristic of the opticalcomponent prior to placing the relative reference mount in the referencesubstrate whereby the optical component is fixed in six degrees offreedom relative to the relative reference mount.
 42. The optical moduleof claim 41 including a bond to fix the spacial location.
 43. Theoptical module of claim 42 wherein the bond comprises solder.
 44. Theoptical module of claim 41 wherein the registration feature isconfigured to provide substantially kinematic registration to thereference substrate.
 45. The optical module of claim 43 wherein the bondhas a first state in which the spacial orientation can be adjusted and asecond state in which the spacial orientation is fixed.
 46. The opticalmodule of claim 42 wherein the bond touches only one of the adjustableoptical component mount and the relative reference mount when in a firststate.
 47. The optical module of claim 42 wherein the bond is activatedto fix the spacial orientation.
 48. The optical module of claim 47wherein application or removal of heat causes a change in state of thebond.
 49. The optical module of claim 41 wherein the relative referencemount is substantially planar.
 50. The optical module of claim 41including a bonding pad between the adjustable optical component mountand the relative reference mount configured to adhere to the bond. 51.The optical module of claim 48 including a heating element carried on atleast one of the relative reference mount and the optical componentmount.
 52. The optical module of claim 41 wherein the optical componentmount comprises silicon.
 53. The optical module of claim 41 wherein theadjusted fixed spacial orientation comprises height of the opticalcomponent over the relative reference mount.
 54. The optical module ofclaim 42 wherein the bond comprises a weld.
 55. An optical module foruse in an optical device, comprising: an optical component having anoptical characteristic which varies based upon a position of the opticalcomponent in space relative to at least one dimension and whereincomponent variability causes a variability in the opticalcharacteristic; a relative reference mount having a registration featurewith a three dimensional shape configured to constrain movement in sixdegrees of freedom when physically coupled to a correspondingregistration feature of a substrate and to provide a repeatableregistration therebetween; an adjustable optical component mountconfigured to fixedly mount the optical component and adjustably mountto the relative reference mount at a prealigned orientation and positionrelative to the registration feature; and a bond configured to fixedlysecure the adjustable optical component mount and thereby the opticalcomponent at the prealigned orientation and position relative to theregistration feature of the relative reference mount to adjust for thevariability in the optical characteristic of the optical component priorto placing the substrate in the fixed reference mount whereby theoptical component is fixed in six degrees of freedom relative to theregistration feature of the relative reference mount.
 56. The opticalmodule of claim 53 wherein the bond comprises solder.
 57. The opticalmodule of claim 55 wherein the optical characteristic is aligned with areference defined relative to the registration feature of the relativereference mount.
 58. The optical module of claim 55 wherein the bondprovides a fixed spacial orientation between the optical component andthe relative reference mount.
 59. The optical module of claim 58 whereinthe bond has a first state in which the spacial orientation can beadjusted and a second state in which the spacial orientation is fixed.60. The optical module of claim 59 wherein the bond is operably coupledto only one of the optical component mount and the relative referencemount when in a first state.
 61. The optical module of claim 55 whereinapplication or removal of heat causes a change in state of the bond. 62.The optical module of claim 55 wherein the bond is heat activated and atleast one heating element is thermally coupled to the bond.
 63. Theoptical module of claim 55 wherein the prealigned position comprises aheight of the optical component over the relative reference mount. 64.The optical module of claim 55 wherein the bond comprises a weld.